(1) Field of the Invention
The present invention relates to a surface deployed navigational beacon, which is nominally secure from nonfriendly forces. More particularly the beacon is capable of user selection of any of a plurality of codes to modulate a transmitted radio signal. The signal is used by the navigational entity to determine direction to the beacon, as well as to distinguish a particular beacon from others which may be deployed within the same broad area. The beacon has the capability of receiving selected coded radio signals sent from the navigating entity. One received signal results in a signal being sent back to the navigating entity from the beacon for the purpose of providing slant range distance between the beacon and the navigating entity. Another signal received by the beacon from the navigating entity is employed to trigger a flare, integral to the beacon assembly, for backup visual/infrared navigational purposes. The surface deployed beacon is capable of place-and-leave or hand-held deployment. The counterpart system, used in conjunction with the marker beacon system, is used by the navigating entity and is contained in an airborne platform such as a cruise missile, search and rescue (SAR) or strike aircraft, or by ground personnel.
(2) Description of the Prior Art
Warfare has evolved to the state where a large segment of any conflict is devoted to the use of aircraft for interdiction strikes on supply sources, supply depots, and arms caches; to the denial of avenues of supply; to the supply, re-enforcing and evacuation of friendly forces located in nonfriendly territory; and tactical strikes. Some of these functions can be performed by cruise missiles as well as by aircraft. To avoid known or suspected concentrations of nonfriendly countermeasures, flights by cruise missiles and aircraft must navigate over circuitous routes, employing intermediate waypoints for navigation. Employing terrain features for waypoint identification is not always feasible or viable. The present invention is useful in solving the above problems.
Evacuation of airmen downed in nonfriendly territory has been, and remains, a problem when the downed airman transmits on the international distress frequency. The SAR aircraft has navigation problems and the nonfriendly forces have the same capability for detection of and homing on that frequency. Similar problems apply to small reconnaissance forces operating in nonfriendly territory who are in need of supply, reenforcement, or evacuation, or have discovered an arms cache which should be the subject of an aerial strike after they depart the area. In this case, the ground forces need to accurately mark the location for strike aircraft, or for the return of ground forces, prior to their departure from the area.
Oftentimes the targets, such as an arms cache or downed airmen, are in areas where a visual sighting from airborne platforms is nigh impossible. Such a situation occurs when a dense jungle canopy is between the target and the airborne platform. The canopy not only obscures visual sighting, but it will also attenuate and scatter radio signals in frequency bands normally employed by ground forces and downed airmen when the transmitter is below a wet canopy.
The prior art discloses some features that could be modified for use in the present invention. However, there appears to be no teaching of combining any of these features to provide a device capable of the functions provided by the present system for broadcasting marker beacon signals and processing responses from seeking entities.